CN115340639A

CN115340639A - Sealing element

Info

Publication number: CN115340639A
Application number: CN202210439721.7A
Authority: CN
Inventors: 平野耕生; 池原润一郎; 牧野大介; 深泽新平; 稻垣朋也
Original assignee: Mitsubishi Cable Industries Ltd
Current assignee: Mitsubishi Cable Industries Ltd
Priority date: 2021-05-13
Filing date: 2022-04-25
Publication date: 2022-11-15
Also published as: EP4089155A1; JP7265583B2; EP4089155C0; JP2022175415A; EP4089155B1

Abstract

The present invention relates to a seal. The seal (10) is formed from a rubber composition. The rubber composition contains a rubber component mainly composed of a hydrogenated nitrile rubber, a fatty acid amide, and carbon black having an average particle diameter of 60nm or less, and the rubber component is crosslinked using an organic peroxide, a co-crosslinking agent, and sulfur.

Description

Sealing element

Technical Field

The present invention relates to a seal.

Background

It is known to use hydrogenated nitrile rubber as a material for forming a seal. For example, JP2015-63634A1 publication discloses a composition containing a carboxyl group-containing hydrogenated nitrile rubber, a hydrogenated nitrile rubber, and a polyamide resin as a rubber composition for forming a seal.

Disclosure of Invention

The present invention relates to an annular seal member formed of a rubber composition containing a rubber component mainly composed of a hydrogenated nitrile rubber, a fatty acid amide, and carbon black having an average particle diameter of 60nm or less, wherein the rubber component is crosslinked using an organic peroxide, a co-crosslinking agent, and sulfur.

Drawings

Fig. 1 is a sectional view showing a structure in which a seal according to an embodiment is attached;

fig. 2 is an explanatory view of the abrasion resistance test method.

-description of symbols-

10-a seal; 21-a housing; 22-cylindrical hole; 23-a seal receiving groove; 24-an interposer; 31-sample; 32-a fixing member; 33-metal plate.

Detailed Description

The following describes embodiments in detail.

Fig. 1 shows a structure in which a seal 10 according to an embodiment is attached. The seal 10 is a so-called O-ring, which is used in the following manner: the seal 10 is fitted into a seal receiving groove 23 formed in an inner peripheral surface of a cylindrical hole 22 in a housing 21, and an axially movable insertion member 24 is inserted into the seal 10 so as to slide along the inner peripheral surface. Specifically, for example, in the solenoid valve, the seal 10 is fitted in an inner peripheral groove (seal accommodating groove 23) of a spool insertion hole (cylindrical hole 22) in a valve main body (housing 21), and a spool (inner insertion member 24) is inserted into the seal 10, so that the seal 10 is interposed between the valve main body and the spool and used as a pneumatic packing.

The seal material 10 according to the embodiment is formed of a rubber composition X containing a rubber component mainly composed of a hydrogenated nitrile rubber (hereinafter referred to as "HNBR"), a fatty acid amide a, and carbon black B having an average particle diameter of 60nm or less, and the rubber component is crosslinked using an organic peroxide P, a co-crosslinking agent Q, and sulfur R.

According to the seal material 10 of the embodiment, the rubber composition X forming the seal material 10 contains the rubber component containing HNBR as the main component, the fatty acid amide a, and the carbon black B, and the rubber component is crosslinked using the organic peroxide P, the co-crosslinking agent Q, and the sulfur R, whereby the seal material 10 can be applied to the use in which the inner peripheral surface thereof is used as the sliding surface.

The content of HNBR in the rubber component is more than 50 mass%, from the viewpoint of obtaining characteristics suitable when the inner peripheral surface of the seal 10 is used as a sliding surface, is preferably 80 mass% or more, more preferably 90 mass% or more, and further preferably 100 mass%. The rubber component may contain, for example, nitrile rubber, silicone rubber, fluororubber, EPDM, or the like in addition to HNBR.

From the viewpoint of obtaining characteristics suitable for use when the inner peripheral surface of the seal 10 is used as a sliding surface, the amount of bound acrylonitrile in HNBR is preferably 18 mass% or more and 52 mass% or less, more preferably 30 mass% or more and 40 mass% or less, and further preferably 35 mass% or more and 37 mass% or less. From the same viewpoint, the iodine value of HNBR is preferably 8mg/100mg to 28mg/100mg, more preferably 10mg/100mg to 15mg/100 mg.

Examples of the fatty acid amide a include erucamide, oleamide, stearic acid amide, behenamide, N-oleyl palmitamide, N-stearyl erucamide ethylene bis stearamide, and methylene bis stearamide. The fatty acid amide a preferably contains one or two or more of the above substances, and preferably contains an unsaturated fatty acid amide, more preferably contains an ω -9 fatty acid amide, and further preferably contains erucamide from the viewpoint of obtaining characteristics suitable when the inner peripheral surface of the seal 10 is used as a sliding surface. From the same viewpoint, the melting point of the fatty acid amide A is preferably 70 ℃ to 90 ℃, more preferably 75 ℃ to 85 ℃.

The content a of the fatty acid amide a in the rubber composition X is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 2 parts by mass or more and 6 parts by mass or less, with respect to 100 parts by mass of the rubber component, from the viewpoint of obtaining characteristics suitable for use when the inner peripheral surface of the seal 10 is used as a sliding surface.

Examples of the carbon black B include FEF, SAF, N234, ISAF, N339, N351, HAF, and MAF. The carbon black B preferably contains one or two or more of the above substances, and more preferably contains FEF from the viewpoint of obtaining characteristics suitable when the inner peripheral surface of the seal 10 is used as a sliding surface.

The average particle diameter of the carbon black B is 60nm or less, and from the viewpoint of obtaining characteristics suitable for use when the inner peripheral surface of the seal 10 is used as a sliding surface, the average particle diameter is preferably 20nm to 60nm, more preferably 20nm to 55nm, still more preferably 25nm to 50nm, and still more preferably 40nm to 45 nm. The average particle diameter of the carbon black B is an arithmetic average particle diameter.

From the viewpoint of obtaining characteristics suitable for use when the inner peripheral surface of the seal 10 is used as a sliding surface, the content B of the carbon black B in the rubber composition X is preferably 10 parts by mass or more and 80 parts by mass or less, more preferably 35 parts by mass or more and 60 parts by mass or less, and further preferably 50 parts by mass or more and 58 parts by mass or less, with respect to 100 parts by mass of the rubber component. From the same viewpoint, the ratio (B/a) of the content B of the carbon black B to the content a of the fatty acid amide a in the rubber composition X is preferably 5 to 20, more preferably 7 to 15, and further preferably 12 to 14.

Examples of the organic peroxide P include: dialkyl peroxides such as dicumyl peroxide, 1,3-di (t-butylperoxy) diisopropylbenzene, 1,4-di (t-butylperoxy) diisopropylbenzene, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane-3; 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-butylperoxy) cyclohexane, n-butyl-4,4-di (t-butylperoxy) valerate, and the like; 2,5-dimethyl-2,5-di (benzoyl peroxide) hexane, tert-hexyl peroxybenzoate, tert-butyl peroxybenzoate, and other peroxyesters.

The organic peroxide P preferably contains one or two or more of the above-mentioned substances, and from the viewpoint of obtaining characteristics suitable when the inner peripheral surface of the seal material 10 is used as a sliding surface, preferably contains a dialkyl peroxide, more preferably contains a dialkyl peroxide having an aromatic ring in the molecule, still more preferably contains a dialkyl peroxide having one aromatic ring in the molecule, and still more preferably contains 1,3-di (tert-butylperoxy) diisopropylbenzene.

From the viewpoint of obtaining properties suitable for use when the inner peripheral surface of the seal 10 is used as a sliding surface, the amount P of the organic peroxide P added to the uncrosslinked rubber composition before crosslinking the rubber composition X is preferably 0.5 parts by mass or more and 5 parts by mass or less, more preferably 1 part by mass or more and 4 parts by mass or less, and still more preferably 2 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the rubber component.

Examples of the co-crosslinking agent Q include: maleimide co-crosslinking agents such as N, N' -m-phenylenebismaleimide, maleimide, phenylmaleimide, etc.; methacrylate co-crosslinking agents such as trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and polyethylene glycol dimethacrylate; allyl co-crosslinking agents such as triallyl cyanurate, diallyl fumarate, diallyl phthalate, tetraallyloxyethane, triallyl isocyanurate, and trimethylallylisocyanurate; 1,2-polybutadiene, and the like. The co-crosslinking agent Q preferably contains one or two or more of the above, and preferably contains a maleimide-based co-crosslinking agent, and more preferably contains N, N' -m-phenylene bismaleimide, from the viewpoint of obtaining characteristics suitable when the inner peripheral surface of the seal member 10 is used as a sliding surface.

From the viewpoint of obtaining characteristics suitable when the inner peripheral surface of the seal member 10 is used as a sliding surface, the addition amount Q of the co-crosslinking agent Q in the uncrosslinked rubber composition before crosslinking of the rubber composition X is preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less, with respect to 100 parts by mass of the rubber component.

From the viewpoint of obtaining characteristics suitable when the inner peripheral surface of the seal material 10 is used as a sliding surface, the ratio (Q/P) of the addition amount Q of the co-crosslinking agent Q to the addition amount P of the organic peroxide P in the uncrosslinked rubber composition before crosslinking of the rubber composition X is preferably 0.8 to 3, and more preferably 1 to 1.5. From the same viewpoint, the addition amount Q of the co-crosslinking agent Q in the uncrosslinked rubber composition before crosslinking of the rubber composition X is preferably larger than the addition amount P of the organic peroxide P.

From the viewpoint of obtaining properties suitable for use when the inner peripheral surface of the seal 10 is used as a sliding surface, the amount R of sulfur R added to the uncrosslinked rubber composition before crosslinking the rubber composition X is preferably 0.1 part by mass or more and 1 part by mass or less, and more preferably 0.2 part by mass or more and 0.6 part by mass or less, relative to 100 parts by mass of the rubber component.

From the viewpoint of obtaining properties suitable for use when the inner peripheral surface of the seal 10 is used as a sliding surface, the ratio (R/P) of the amount R of sulfur R added to the uncrosslinked rubber composition before crosslinking of the rubber composition X to the amount P of organic peroxide P added is preferably 0.03 to 0.3, more preferably 0.1 to 0.5, and still more preferably 0.15 to 0.2. From the viewpoint of obtaining characteristics suitable for use when the inner peripheral surface of the seal material 10 is used as a sliding surface, the ratio (R/Q) of the addition amount R of the sulfur R in the uncrosslinked rubber composition before crosslinking of the rubber composition X to the addition amount Q of the co-crosslinking agent Q is preferably 0.04 to 0.2, and more preferably 0.1 to 0.15.

The rubber composition X may contain a processing aid, an antiaging agent, a plasticizer, a vulcanization accelerator aid, and the like in addition thereto.

The hardness Hs of the rubber composition X is preferably a60 to a 95. The hardness Hs is based on JIS K6253-3:2012, measured with a type a durometer.

The tensile strength Tb of the rubber composition X is preferably 10MPa or more. The elongation Eb of the rubber composition X is preferably 200% or more. The tensile stress S100 of the rubber composition X at an elongation of 100% is preferably 1MPa or more and 10MPa or less. The tensile strength Tb, the elongation Eb, and the tensile stress S100 at 100% are based on JIS K6251: 2017.

The compression set CS of the rubber composition X is preferably 20% to 40%, more preferably 25% to 35%. The compression set CS is based on JIS K6262:2013, measured at a test temperature of 120 ℃ and a test time of 72 hours.

The tear strength TS of the rubber composition X is preferably 50N/mm or more. The tear strength TS is based on JIS K6252-1:2015 measured.

Next, a method for manufacturing the seal 10 according to the embodiment will be described.

First, a rubber component containing HNBR is put into a rubber mixer such as an internal mixer, and masticated, and various rubber additives containing a fatty acid amide a, carbon black B, an organic peroxide P, a co-crosslinking agent Q, and sulfur R are added thereto and kneaded, thereby preparing an uncrosslinked rubber composition.

Next, a predetermined amount of the prepared uncrosslinked rubber composition is filled in a cavity having the shape of the seal 10 formed in a mold, the mold is closed, and a rubber component of the uncrosslinked rubber composition is primarily crosslinked by press molding in which heating at a predetermined temperature (for example, 165 to 175 ℃) and pressurization at a predetermined pressure (for example, 10 to 20 MPa) are performed for a predetermined time (for example, 5 to 15 minutes) to obtain a primary crosslinked product.

Then, after releasing the primary crosslinked material from the mold, the resultant is put into an oven and annealed to secondarily crosslink the rubber component, thereby obtaining the sealing material 10 according to the embodiment, wherein the heating is performed at a temperature lower than that of the primary crosslinking (for example, 140 ℃ to 160 ℃) and for a time longer than that of the primary crosslinking (for example, 3 hours to 5 hours).

[ examples ]

(uncrosslinked rubber composition)

The following uncrosslinked rubber compositions of example 1 and comparative examples 1 to 4 were prepared. The respective configurations are also shown in table 1.

< example 1 >

An HNBR (bound acrylonitrile amount: 36.2 mass%, iodine value: 11mg/100 mg) rubber component was formed, and to 100 parts by mass of the rubber component, 4 parts by mass of erucamide as a fatty acid amide, 55 parts by mass of FEF (average particle diameter: 43 nm) as carbon black, 5.5 parts by mass of a processing aid, 3 parts by mass of an antioxidant, 5 parts by mass of a plasticizer, 5 parts by mass of a vulcanization accelerator, 2.4 parts by mass of 1,3-di (t-butylperoxy) diisopropylbenzene as an organic peroxide, 3 parts by mass of N, N' -m-phenylene bismaleimide as a co-crosslinking agent, and 0.4 part by mass of sulfur were added and kneaded to obtain an uncrosslinked rubber composition, which was set as example 1.

< comparative example 1 >

An uncrosslinked rubber composition was prepared in the same manner as in example 1 except that erucamide as a fatty acid amide was not added and the amount of the processing aid added was 1.5 parts by mass with respect to 100 parts by mass of the rubber component, and the uncrosslinked rubber composition was set as comparative example 1.

< comparative example 2 >

An uncrosslinked rubber composition was prepared in the same manner as in example 1 except that SRF (average particle diameter: 66 nm) as carbon black was added in place of FEF as carbon black, and the above uncrosslinked rubber composition was set as comparative example 2.

< comparative example 3 >

An uncrosslinked rubber composition was prepared in the same manner as in example 1 except that N, N' -m-phenylene bismaleimide as a co-crosslinking agent was not added, and the uncrosslinked rubber composition was set as comparative example 3.

< comparative example 4 >

An uncrosslinked rubber composition was prepared in the same manner as in example 1 except that no sulfur was added, and the above uncrosslinked rubber composition was set as comparative example 4.

[ Table 1]

(test methods and results thereof)

A sample of the rubber composition was prepared from the uncrosslinked rubber composition, and the following test was carried out using this sample. The results are shown in table 1.

Hardness

Using the uncrosslinked rubber compositions of example 1 and comparative examples 1 to 4, respectively, predetermined test specimens were prepared in accordance with JIS K6253-3:2012, hardness Hs was measured with a type a durometer. In the preparation of the sample, the temperature condition for the primary crosslinking was 170 ℃ and the time condition was 10 minutes, and the temperature condition for the secondary crosslinking was 150 ℃ and the time condition was 4 hours (the same applies hereinafter).

< tensile Property >

Using the uncrosslinked rubber compositions of example 1 and comparative examples 1 to 4, respectively, predetermined samples were prepared based on JIS K6251:2017, the tensile strength Tb, the elongation Eb and the tensile stress S100 at 100% elongation were measured.

< tear Strength >

The uncrosslinked rubber compositions of example 1 and comparative examples 1 to 2 were used to prepare predetermined notched test specimens in accordance with JIS K6252-1:2015, tear strength TS is measured using test method B.

< compression set >

Using the uncrosslinked rubber compositions of example 1 and comparative examples 1 to 4, respectively, predetermined samples were prepared in accordance with JIS K6262:2013, the compression set rate CS was measured under the conditions that the test temperature was 120 ℃ and the test time was 72 hours.

< abrasion resistance >

Using the uncrosslinked rubber compositions of example 1 and comparative examples 1 to 2, respectively, cylindrical samples having a diameter of 6.3mm and a height of 8.0mm were prepared, and as shown in fig. 2, the sample 31 was fixed by a fixture 32 and the sample 31 was pressure-bonded to a metal plate 33, and in this state, the metal plate 33 was reciprocated so that the bottom surface of the sample 31 was in sliding contact with the metal plate 33. The material of the metal plate 33 was SS400, the surface roughness Ry was 3.2, and the finishing direction was a direction perpendicular to the sliding direction. The pressing pressure of the sample 31 against the metal plate 33 was set to 0.1MPa, the number of round trips of the metal plate 33 was set to 60 times/minute, the round trip stroke of the metal plate 33 was set to 10mm, and the number of round trips of the metal plate 33 was set to 10 ten thousand times. Then, the wear amount (mm) was calculated by dividing the decrease in mass of the sample 31 before and after the test by the specific gravity of the sample 31 and then by the area of the bottom surface.

Claims

1. A seal member formed of a rubber composition and having a ring shape, characterized in that:

the rubber composition contains a rubber component mainly composed of a hydrogenated nitrile rubber, a fatty acid amide, and carbon black having an average particle diameter of 60nm or less, and the rubber component is crosslinked using an organic peroxide, a co-crosslinking agent, and sulfur.

2. The seal of claim 1, wherein:

the amount of bound acrylonitrile in the hydrogenated nitrile rubber is 18 to 52 mass%.

3. The seal of claim 1, wherein:

the iodine value of the hydrogenated nitrile rubber is more than 8mg/100mg and less than 28mg/100 mg.

4. The seal of claim 1, wherein:

the fatty acid amide comprises an unsaturated fatty acid amide.

5. The seal of claim 1, wherein:

the content of the fatty acid amide in the rubber composition is 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

6. The seal of claim 1, wherein:

the carbon black comprises FEF.

7. The seal of claim 1, wherein:

the average particle diameter of the carbon black is 20nm to 60 nm.

8. The seal of claim 1, wherein:

the content of the carbon black in the rubber composition is 10 to 80 parts by mass with respect to 100 parts by mass of the rubber component.

9. The seal of claim 1, wherein:

in the rubber composition, the ratio of the content of the carbon black to the content of the fatty acid amide is 5 to 20.

10. The seal of claim 1, wherein:

the organic peroxide comprises a dialkyl peroxide.

11. The seal of claim 1, wherein:

the co-crosslinking agent comprises a maleimide co-crosslinking agent.

12. The seal of claim 1, wherein:

in the uncrosslinked rubber composition before crosslinking of the rubber composition, the ratio of the addition amount of the co-crosslinking agent to the addition amount of the organic peroxide is 0.8 or more and 3 or less.

13. The seal of claim 1, wherein:

in the uncrosslinked rubber composition before crosslinking of the rubber composition, the addition amount of the co-crosslinking agent is larger than that of the organic peroxide.

14. The seal of claim 1, wherein:

in the uncrosslinked rubber composition before crosslinking, the ratio of the amount of sulfur added to the amount of the organic peroxide added is 0.03 to 0.3.

15. The seal of claim 1, wherein:

in the uncrosslinked rubber composition before crosslinking of the rubber composition, the ratio of the amount of the sulfur added to the amount of the co-crosslinking agent added is 0.04 or more and 0.2 or less.